1. Field of the Invention
The present invention relates to a display system, and more particularly to an apparatus and method for increasing the pixel resolution of an input image using coherent sampling.
2. Description of the Related Art
Display systems are employed to process input images from one or more video source devices, like DVD player or computer etc., into output images to be displayed on a corresponding display screen of monitors or televisions. Usually, the input image is transmitted from a computer host or a video source such that the pixel resolution of the input image has been predetermined. Therefore, the display system needs a scaler to resize or scaled the predetermined pixel resolution of the input image into an appropriate pixel resolution such that the display screen can correctly display the output image. The input image signal provided by a computer is generally complying with the VESA format, a computer graphics format.
Modern video and image display devices are now often characterized by having a display panel with a fixed pixel resolution. Well-known examples are LCD monitors and LCD televisions. These modern display panels also typically accept only digital source images. Since the images or image sequences from many video sources are still transmitted from the video source device to the display device using analog signal formats the display device now requires an ADC (analog-to-digital-converter) which samples and digitizes the analog video signal input. The ADC of the conventional display controller samples the analog signal at a time interval that results in a pixel resolution at the ADC output that mirrors the native resolution of the video source. Often this pixel resolution is lower than the pixel resolution of the display panel. Directly displaying the digitized image on the output display panel would then result in an image that does not fill the entire display area, as shown in FIG. 6. Digital scaling methods are typically used to increase the resolution of the image to fit the display panel. FIG. 7 shows the typical function blocks of currently used upscaling technology.